Study On Multi-level Cascaded Power Inverter Control Method

Compared to the two-level inverter, the multi-level inverter can use low-voltage switch to bear high voltage through the cascaded way. Compared to the high voltage switch, low voltage switch is faster, smaller and cheaper. The multi-level inverter can also provide the waveform of less harmonic contents, closer to the pure sine wave shape, so that the size and cost for the output filter may be largely reduced. Under the same total harmonic distortion condition, the multi-level inverter can use lower switching frequency, so the switching losses are lower. In addition, because of its cascade topology, each level and its magnitude is correspondingly smaller, and therefore the output voltage and the dv/ dt is relatively small so the impact on the cable and the motor are reduced. For multi-level cascaded converters, there are three available typologies in the literature,they are diode clamped inverter, flying capacitor inverter and cascaded H-bridge inverter.In this article, I will study the multi-level circuit topology and the characteristic of cascaded inverters. Analyse and compare individually their modes of operation, advantages and disadvantages, and technical and economic indicators, and a comprehensive comparison,evaluation and simulation calculation of theoretical aspects of its in-depth discussion, the applicable range of operating conditions and the key issues in terms of practical applications.